Aerosol generating apparatus and method of operating same

Abstract

An aerosol generating apparatus has a composite susceptor for heating an aerosol generating material in use thereby to generate an aerosol. The composite susceptor comprises a support portion and a susceptor portion supported by the support portion. The apparatus comprises an induction element arranged for inductive energy transfer to the susceptor portion in use; and a driving arrangement arranged to drive the induction element with an alternating current in use thereby to cause the inductive energy transfer to the susceptor portion, thereby to cause the heating of the aerosol generating material by the composite susceptor, thereby to generate the aerosol. The alternating current has a waveform comprising a fundamental frequency component having a first frequency and one or more further frequency components each having a frequency higher than the first frequency. A method of operating the aerosol generating apparatus is also disclosed.

The invention claimed is: 
     
       1. An aerosol generating apparatus comprising:
 a composite susceptor for heating an aerosol generating material in use thereby to generate an aerosol in use, wherein the composite susceptor comprises a support portion and a susceptor portion supported by the support portion; 
 an induction element arranged for inductive energy transfer to the susceptor portion in use; and 
 a driving arrangement configured to drive the induction element with an alternating current in use thereby to cause the inductive energy transfer to the susceptor portion in use, thereby to cause the heating of the aerosol generating material by the composite susceptor in use, thereby to generate the aerosol in use; 
 wherein the alternating current has a waveform comprising a fundamental frequency component having a first frequency and one or more further frequency components each having a frequency higher than the first frequency. 
 
     
     
       2. The aerosol generating apparatus according to  claim 1 , wherein the susceptor portion is a coating on the support portion. 
     
     
       3. The aerosol generating apparatus according to  claim 1 , wherein the susceptor portion has a thickness of no more than 50 microns. 
     
     
       4. The aerosol generating apparatus according to  claim 1 , wherein the susceptor has a thickness of no more than 20 microns. 
     
     
       5. The aerosol generating apparatus according to  claim 1 , wherein the susceptor portion comprises a ferromagnetic material. 
     
     
       6. The aerosol generating apparatus according to  claim 1 , wherein the susceptor portion comprises one or more of nickel, aluminum, and cobalt. 
     
     
       7. The aerosol generating apparatus according to  claim 1 , wherein the one or more further frequency components are harmonics of the fundamental component. 
     
     
       8. The aerosol generating apparatus according to  claim 1 , wherein the first frequency is a frequency F in the range 0.5 MHz to 2.5 MHz, and the frequency of each of the one or more further frequency components is nF, where n is a positive integer greater than 1. 
     
     
       9. The aerosol generating apparatus according to  claim 1 , wherein the waveform is one of a triangular waveform, a sawtooth waveform, and a square waveform. 
     
     
       10. The aerosol generating apparatus according to  claim 1 , wherein the waveform is a bi-polar square waveform and wherein the driving arrangement comprises transistors arranged in a H-bridge configuration and controllable to provide the bi-polar square waveform. 
     
     
       11. The aerosol generating apparatus according to  claim 1 , wherein the composite susceptor is substantially planar. 
     
     
       12. The aerosol generating apparatus according to  claim 1 , wherein the composite susceptor is substantially tubular. 
     
     
       13. The aerosol generating apparatus according to  claim 1 , wherein the susceptor portion comprises a first sheet of a first material and the support portion comprises a second sheet of a second material configured to abut the susceptor portion to support the susceptor portion, wherein the first material and the second material may be the same or different from one another. 
     
     
       14. The aerosol generating apparatus according to  claim 13 , wherein the support portion is configured to surround the susceptor portion. 
     
     
       15. The aerosol generating apparatus according to  claim 13 , wherein the second material is one or more materials selected from the group consisting of a metal, a metal alloy, a ceramic material, a plastic material, and paper. 
     
     
       16. The aerosol generating apparatus according to  claim 1 , wherein the composite susceptor comprises a heat resistant protective portion, wherein the susceptor portion is located between the support portion and the protective portion. 
     
     
       17. The aerosol generating apparatus according to  claim 16 , wherein the heat resistant protective portion is a coating on the susceptor portion. 
     
     
       18. The aerosol generating apparatus according to  claim 16 , wherein the heat resistant protective portion is made of one or more materials selected from the group consisting of a ceramic material, a metal nitride, a titanium nitride, and diamond. 
     
     
       19. The aerosol generating apparatus according to  claim 1 , wherein the apparatus comprises the aerosol generating material, wherein the aerosol generating material is arranged in thermal contact with the composite susceptor. 
     
     
       20. The aerosol generating apparatus according to  claim 19 , wherein the aerosol generating material comprises tobacco and/or one or more humectants. 
     
     
       21. A method of operating an aerosol generating apparatus, the aerosol generating apparatus comprising a composite susceptor arranged for heating an aerosol generating material thereby to generate an aerosol, the composite susceptor comprising a support portion and a susceptor portion supported by the support portion; the apparatus further comprising an induction element arranged for inductive energy transfer to the susceptor portion; the method comprising:
 driving the induction element with an alternating current thereby to cause the inductive energy transfer to the susceptor portion, thereby to cause the heating of the aerosol generating material by the composite susceptor, thereby to generate the aerosol; 
 wherein the alternating current has a waveform comprising a fundamental frequency component having a first frequency and one or more further frequency components each having a frequency higher than the first frequency. 
 
     
     
       22. The method according to  claim 21 , wherein the one or more further frequency components are harmonics of the fundamental frequency component. 
     
     
       23. The method according to  claim 21 , wherein the first frequency is a frequency F in the range 0.5 MHz to 2.5 MHz, and the frequency of each of the one or more further frequency components is nF, where n is a positive integer greater than 1. 
     
     
       24. The method according to  claim 21 , wherein the waveform is one of a triangular waveform, a sawtooth waveform, a bi-polar square waveform, and a square waveform.